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bio website lightandmatter.com
location Fullerton, California
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I teach physics at Fullerton College, a community college in Southern California. I have an undergrad degree in math and physics from Berkeley and a PhD in physics from Yale. Back when I was doing research, my field was experimental low-energy nuclear physics.


1d
comment Leading-order cause of diurnal (not semidiurnal) variations in $g$?
@user_of_math: I'm expressing them as fractions of $g$. The factor of 10 is from $g\approx 10$ m/s2.
1d
comment Variation in measurements of $g$ on the Earth's surface due to the Moon's gravity
related: physics.stackexchange.com/questions/128816/…
1d
comment Are we slightly lighter during the day and slightly heavier at night, owing to the force of the Sun's gravity?
related: physics.stackexchange.com/questions/128816/…
1d
comment How accurately can I expect to measure the gravitational constant with a club of college students?
This may be of interest: Abellán-García et al, Gravity acceleration measurements using a soundcard, iopscience.iop.org/0143-0807/33/5/1271?rel=ref&relno=3
1d
comment Are we slightly lighter during the day and slightly heavier at night, owing to the force of the Sun's gravity?
@Floris: If it was a thermal effect, I would think it would be very hard to calculate so accurately...? I don't know. Does Squires explain it at all? I don't have access to the Zumberge paper.
1d
comment Why does the fundamental mode of a recorder disappear when you blow harder?
I don't think this can be right, since it would seem to predict a gradual change rather than a sudden one.
1d
comment Woodwind instruments overtones
possible duplicate of Why does the fundamental mode of a recorder disappear when you blow harder?
1d
comment Intuitive explaination for why higher engine compression ratio is more efficient?
Shouldn't "more efficient" be "higher in torque?"
1d
comment Are we slightly lighter during the day and slightly heavier at night, owing to the force of the Sun's gravity?
What is the origin of the Fourier component with a period of 24 hours?
2d
comment Variation in measurements of $g$ on the Earth's surface due to the Moon's gravity
@dmckee: You may be right. I was just trying to figure out how they got their answer, and it seemed like the erroneous calculation needed to get their numerical result would also result in a prediction of a 24-hour period, which would probably be the more common interpretation of "diurnal."
2d
comment How accurately can I expect to measure the gravitational constant with a club of college students?
@DavidHammen might be interested in this: physics.stackexchange.com/questions/128691/…
2d
comment In a Big Crunch, would there be more mass than at the Big Bang?
@Jim: You could edit the answer to make the language more precise, but then I think it would become clear that point B is irrelevant to the question. It's not a matter of probability whether or not we will have a Big Crunch. We know that there will not be. The question asks about a hypothetical cosmology that is not a realistic model of our own universe.
2d
comment In a Big Crunch, would there be more mass than at the Big Bang?
Point B is wrong. In the $\Omega_M$-$\Omega_\Lambda$ plane, there is a boundary between cosmologies that lead to an eventual recollapse and those that don't. Positive values of $\Omega_\Lambda$ can be compatible with a Big Crunch.
Jul
28
comment On the coordinate independence of general relativity
This doesn't answer the question.
Jul
28
comment Why are AC quantities represented by sine waves always?
The crucial mathematical property of sinusoidal waves is that if you add two sinusiodal waves with the same frequency, you get another sinusoidal wave. Square waves, etc., don't have this property.
Jul
26
comment Can the distance over time of an electron between two measurements be higher than the speed of light?
The first paragraph doesn't address the question. The second and third paragraphs are an example, but an example doesn't prove a general rule. The final paragraphs don't address the question, since the question asks about the outcome of a measurement process, which is manifestly well defined.
Jul
26
comment Can the distance over time of an electron between two measurements be higher than the speed of light?
related: physics.stackexchange.com/q/107261
Jul
26
comment Can the distance over time of an electron between two measurements be higher than the speed of light?
I also don't understand the relevance of the Bohr-model calculation.
Jul
26
comment Can the distance over time of an electron between two measurements be higher than the speed of light?
Why is it relevant that the time you found is greater than the Planck time?
Jul
26
comment Can statistical mechanics explain the second law completely?
This all hangs on the claim that "the right laws of probability [...] are inherently T-breaking," because we average over the initial states but sum over the final states. But you then have to show that this asymmetry is more fundamental than the 2nd law of thermodynamics. You're begging the question -- if the 2nd law hasn't been established, we can't apply your probability rule, since we can't define "initial" and "final." Has this argument been published in more detail? I don't find it in this recent review: plato.stanford.edu/archives/fall2011/entries/time-thermo